Grease extraction system, particulate extractor, and method

ABSTRACT

A grease extractor is provided with a frame, a first array of convex baffle plates, a second array of concave baffle plates, and a steam ejector. The first array of convex baffle plates is carried by the frame in spaced-apart relation, so as to provide a first ventilation slot between adjacent, convex baffle plates. The second array of concave baffle plates is carried by the frame in spaced-apart relation, so as to provide a second ventilation slot between adjacent, concave baffle plates. A selected one of the concave baffle plates is offset from a respective, downstream convex baffle plate such that the first ventilation slot opens into a base portion of the concave baffle plate. The steam ejector is supported proximate each ventilation slot for delivering steam into the first ventilation slot and toward a respective one of the concave baffle plates. A method is also provided.

RELATED PATENT DATA

This application claims priority from U.S. Provisional PatentApplication Ser. No. 60/637,264, which was filed Dec. 17, 2004, andwhich is incorporated by reference herein.

TECHNICAL FIELD

The present invention pertains to kitchen ventilation systems. Moreparticularly, the present invention relates to grease extractors forkitchen ventilating systems, such as kitchen exhaust hood assemblies.

BACKGROUND OF THE INVENTION

It is previously known to use porous filter-type grease extractorssupported within a frame to extract grease from contaminated air that isbeing drawn into a kitchen exhaust hood assembly. One such constructionuses a metal mesh that is contained within an outer peripheral frame toprovide a modular grease filter for an exhaust hood. However, porousfilter-type grease extractors tend to be relatively inefficient atextracting grease from contaminated air in an exhaust hood. Hence,grease is typically carried into exhaust ducts and components of theexhaust hood, which reduces airflow over time and creates a potentialfire hazard. Secondly, the screens tend to clog, and they have to beremoved and cleaned periodically.

Another technique uses a series of baffles configured in a frame toextract grease and other contaminants from air that is being drawn intoa kitchen exhaust hood assembly. U.S. Pat. No. 3,945,812 discloses onesuch baffle-type grease extractor that is configured in a removable,modular assembly that can be used to replace porous-type greaseextractors. The modular assembly facilitates installation and cleaningof the baffle-type grease extractor. The baffles creates a circuitousairflow paths that redirect and divert exhaust air that is being drawninto an exhaust hood which causes grease and contaminants to bedeposited onto the interior surfaces of the baffles. However, thecircuitous paths do not trap enough of the grease, in many cases, morethan half of the grease may still pass through the grease extractor andup into the ventilation system of the hood, including the airflow ductsand hood. This has an undesirable effect of reducing airflow andefficiency of the ventilation system. Secondly, buildup of grease withinthe ventilation system, downstream of the baffles, increases a risk offires in the ventilation system. In many cases, the baffle-type greaseextractors need to be periodically removed and cleaned.

Accordingly, further improvements are needed for grease extractors inorder to increase efficiency and performance of grease extractionsystems for cooking environments including those for commercial (orrestaurant) usage and home usage.

SUMMARY OF THE INVENTION

A highly efficient grease extractor includes multiple arrays of baffleplates that are configured to provide a circuitous path in combinationwith a steam ejector in order to generate more efficient and effectiveextraction of grease from ventilated cooking gases and air.

According to one aspect, a grease extractor is provided with a frame, afirst array of convex baffle plates, a second array of concave baffleplates, and a steam ejector. The first array of convex baffle plates iscarried by the frame in spaced-apart relation, so as to provide a firstventilation slot between adjacent, convex baffle plates. The secondarray of concave baffle plates is carried by the frame in spaced-apartrelation, so as to provide a second ventilation slot between adjacent,concave baffle plates. A selected one of the concave baffle plates isoffset from a respective, downstream convex baffle plate such that thefirst ventilation slot opens into a base portion of the concave baffleplate. The steam ejector is supported proximate each ventilation slotfor delivering steam into the first ventilation slot and toward arespective one of the concave baffle plates.

According to another aspect, a ventilation filter for a cooking deviceis provided with an array of parallel, spaced-apart convex channels, anarray of parallel, spaced-apart concave channels, an array of parallel,spaced-apart plates, and a steam pipe. The array of parallel,spaced-apart concave channels is offset a half-mode and internested withthe convex channels to provide circuitous flow paths therebetween. Thearray of parallel, spaced-apart plates is offset a half-mode from theconcave channels. The steam pipe is provided between adjacent ones ofthe concave channels and is configured to direct steam into a slotbetween the adjacent convex channels.

According to yet another aspect, a method is provided for extractinggrease from cooking exhaust fumes. The method includes: providing agrease extractor with convex baffle plates, adjacent axial slots, andconcave baffle plates offset a half-mode from the convex baffle plates;directing flow over the convex baffle plates and into the adjacent axialslots; delivering steam into the axial slots in a same direction asflowing exhaust fumes; splitting flow of exhaust fumes and steam exitingthe axial slots into the concave baffle plates into lateral, opposingdirections, and directing the flow into a direction reversing thedirection of flow in the axial slots, and into the concave side of theconvex baffle plates; and diverting flow from the concave side of theconvex baffle plates into the second axial slots provided betweenadjacent concave baffle plates.

One advantage is provided by more efficient and thorough extraction ofgrease from exhaust fumes entering a kitchen ventilation system.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a simplified perspective view of a kitchen grill andventilation system having grease extractors according to one aspect ofthe present invention, and showing an exhaust hood in partial breakawayview.

FIG. 2 is a simplified perspective view of a kitchen ventilation systemhaving grease extractors according to another aspect of the presentinvention.

FIG. 3 is an enlarged partial breakaway perspective view of a selectedgrease extractor of FIG. 1 and showing configuration of the baffles andsteam ejectors.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3 and showingarrangement of convex baffle plates, concave baffle plates, and steamejectors in the grease extractor.

FIG. 5 is a further enlarged portion of the sectional view of FIG. 4 andshowing a diagrammatic representation of exhaust gases, ventilation air,and grease being drawn through the grease extractor of FIGS. 1 and 2-4.

FIG. 6 is a plan view of a selected grease extractor of FIG. 1 andshowing an inlet side of the grease extractor in plan view.

FIG. 7 is a partial and breakaway view of a top corner portion of agrease extractor taken from region 7 of FIG. 6.

FIG. 8 is a partial and breakaway view of a top center portion of agrease extractor taken from region 8 of FIG. 6.

FIG. 9 is a partial and breakaway view of a bottom end portion of agrease extractor taken from region 9 of FIG. 6.

FIG. 10 is a partial and breakaway view of a bottom center portion of agrease extractor taken from region 10 of FIG. 6.

FIG. 11 is a top edge partial breakaway view relative to the view ofFIG. 6 and showing arrangement of the baffles.

FIG. 12 is a plan view showing an outlet side of the grease extractor ofFIG. 6, but with the diffuser panel removed to show the third bafflepanel.

FIG. 13 is a longitudinal side view of a selected steam ejector pipefrom the grease extractor of FIG. 6 taken from a downstream end andshowing ejector nozzles on the pipe.

FIG. 14 is a top end view of the steam ejector pipe taken from the rightof FIG. 13 and showing an inlet for receiving steam into the pipe.

FIG. 15 is a partial breakaway longitudinal side view of the steamejector pipe of FIG. 13 and showing an entrance end with an opening andan exit end with a plug.

FIG. 16 is a further enlarged partial breakaway longitudinal side viewof FIG. 15.

FIG. 17 is a top end view of the pipe of FIG. 16 and enlarged over thatdepicted in FIG. 14.

FIG. 18 is a partial sectional view of a steam channel taken along a topportion of the grease extractor taken along line 18-18 of FIG. 6.

FIG. 19 is a partial sectional view of an effluent channel taken along abottom portion of the grease extractor taken along line 19-19 of FIG. 6.

FIG. 20 is a partial breakaway side view of the grease extractor takenthrough a solid frame bar and showing the clamp assemblies for removablymounting the grease extractor into a kitchen exhaust hood.

FIG. 21 is an enlarged partial sectional view of the steam channel ofFIG. 18 taken along line 21-21 of FIG. 6.

FIG. 22 is an enlarged partial sectional view of the effluent channel ofFIG. 19 taken along line 22-22 of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

Reference will now be made to preferred embodiments of Applicant'sinvention comprising grease extractors for use with kitchen ventilationsystems over kitchen ranges, grills, griddles, and/or fryers. While theinvention is described by way of preferred embodiments, it is understoodthat the description is not intended to limit the invention to suchembodiments, but is intended to cover alternatives, equivalents, andmodifications which may be broader than the embodiments, but which areincluded within the scope of the appended claims.

In an effort to prevent obscuring the invention at hand, only detailsgermane to implementing the invention will be described in great detail,with presently understood peripheral details being attached as anappendix, as needed, as being presently understood in the art.

FIG. 1 illustrates a kitchen ventilation system 10 having a ventilationhood 12 containing a hood manifold 14 in which a pair of greaseextractors, or grease extraction modules, 20 are supported side-by sidefor extracting grease and contaminants from cooking gases and air thatis being ventilated from beneath hood 12. Manifold 14 includes a pair ofsidewalls 13 and 15, a front wall 16, and a top wall 17. Front wall 16cooperates with the sidewalls 13 and 15 and a back wall 42 to provide amanifold opening framework 19. Grease extractors 20 are removablyreceived within framework 19. One suitable size for grease extractors 20are 172 inches by 38 inches. Other sizes are also possible.

Hood manifold 14 mates with an exhaust duct 18 that draws air, fumes,contaminants and grease up into grease extractors 20 where the greaseand contaminants are separated from the air and fumes and collected fordelivery via an effluent pipe 26 for collection within a waste housing,or weir 28. Exhaust duct 18 is couple at a downstream location with aventilation exhaust fan (not shown) that pulls exhaust through greaseextractors 20 up into duct 18 for delivery (typically) outside of abuilding.

Hot steam is generated at a source, such as a steam generator 32 fordelivery via a steam inlet pipe 30 to grease extractors 20 by way ofindividual steam inlet assemblies 44 into each grease extractor 20. Thesteam helps capture grease particles and contaminants that are airbornewithin the air and fumes being pulled through grease extractors 20.Assemblies 44 are covered up by a metal facia plate 24 that is removablymounted onto grease extractors 20.

Accumulated grease and contaminants are collected in the bottom of eachgrease extractor 20 where they are drawn out via individual effluentoutlet assemblies 46 for delivery via effluent pipe 26 to waste housing28. Assemblies 46 are covered up by a metal facia plate 22 that isremovably mounted onto grease extractors 20.

As shown in FIG. 1, ventilation hood 12 is provided above one or morecooking appliances, such as a kitchen range, a griddle, a grease fryer38, and/or a toaster 40. Many of such appliances tend to generate greasealong with smoke (and particulates) when cooking food under hood 12.Grease extractors 20 are operative to facilitate capture and removal ofgrease and airborne contaminants from air and cooking gases that aredrawn up into hood 12 via a ventilation exhaust fan.

FIG. 2 illustrates an alternative construction for grease extractors1020 over those depicted in FIGS. 1 and 3-22. More particularly, greaseextractors 1020 are shorter in length than those depicted in FIG. 1. Onesuitable size is 17.2 inches×20 inches. Other sizes are suitable. Greaseextractors 1020 are removably mounted within a ventilation hood 1012,inside of a hood manifold 1014. Upper and lower trim panels 1024 and1022, respectively, cover up steam an effluent delivery lines extendingbetween adjacent grease extractors 1020. Exhaust gases are ventilated upan exhaust duct 18 in response to action of an exhaust fan (not shown)that is typically provided downstream of hood 12.

Hood 1012 also includes a fire suppression system comprising supplypipes 50 and fire suppression emitters 52 that suspend in front of frontwall 1016. Either fire retardant, or water, can be emitted from suchsystem in order to put out cooking fires.

FIG. 3 illustrates in detail the circuitous path that cooking gases,air, grease, and airborne contaminants take as they are drawn through aselected grease extractor 20. More particularly, contaminated hot air isdrawn up from a cooking appliance through a front side of greaseextractor 20 as a result of an exhaust fan (not shown) that is providedbehind the grease extractors 20 (typically at a downstream end of anexhaust hood). The contaminated hot air passes through slots 79 in afirst array 54 of baffle plates 64 and 66, then passes around a secondarray 56 of baffle plates 68, and then passes through slots 80 in athird array 58 of baffle plates 70 and 72. The tortuous path provided byarrays 54, 56 and 58 helps collect and precipitate out grease and otherairborne contaminants from the contaminated hot air. In addition, steamis injected directly into slots 78 via steam pipes (or ejectors) 76provided along an upstream of each slot 78. It has been discovered thatsuch steam injection into slots 78 further increases the efficiency andability to capture grease and contaminants within grease extractor 20.

Additionally, baffles 64 and 66 of array 54 are constructed fromstainless steel according to one configuration. Also, baffles 68 ofarray 56 are constructed from aluminum. Likewise, baffles 70 and 72 arealso constructed from aluminum. Finally, diffuser panel 74 isconstructed from a sheet of 1/16″ thick aluminum that is perforated withapertures, or holes (see FIG. 3), to provide a surface area withapertures that cover 30-40% of the total surface area of the sheet.Steam pipes 76 are constructed from stainless steel tubing, according toone construction. It is understood that alternative materials can alsobe used for these components. Likewise, panel 74 can be constructed withother configurations or aperture sizes and shapes.

As shown in FIG. 3, baffles 64, 66, 68, 70 and 72 are supported at topand bottom edges by frame 60. Additionally, diffuser panel 74 is affixedonto a back surface of array 58 via a plurality of threaded fasteners(not shown). More particularly, the baffles have tabs on their top andbottom ends that fit into slots in the frame. After assembly, the tabsare twisted to lock the baffles into place. For example, baffle 68 has atab 90 at each end that is twisted after insertion into a slot in frame60.

Baffles 64 and 66 of first array 54 each have a flange 94 that forms aconvex portion. Each flange 94 turns back toward pipe 76 to form areverse flange 96. Slot 78 is provided between adjacent flanges 94 forpassage of contaminated air, as well as for injection of steam thereinfrom apertures along steam pipe 76. Furthermore, baffles 70 and 72include concave portions provided by flanges 100. A front flange 92covers a square tube 76 that forms an effluent collection manifold 130that collects grease and contaminants via drain holes 97 (see FIG. 4)and 99. Flange 92 cooperates with solid stainless steel bars, such asbar 62, and tube 76 to form frame 60.

In operation, contaminated air is drawn through slots 78 and into greaseextractor 20 in response to a kitchen ventilation system pulling airthrough extractor 20. The contaminated air goes through slot 78 andsplits into two diverging paths 82 and 84 which double back 180 degrees.The air then reverses again after clearing flange 98 of baffle 68. Theair then follows a respective path 86 and 88 when the split paths rejoinand exit via slot 80. The air further passes through perforations inperforated diffuser panel 74 before being drawn through an exhaust duct(not shown).

According to one implementation, steam in the range of 140-180 degreesFarenheight is delivered into slots 78. When contaminated air dropsbelow approximately 140 degrees Farenheight, suspended contaminants andgrease tend to precipitate out from the steam and onto baffle surfaces.As the steam and contaminated air is mixed in slot 78, the contaminantsand grease are put into suspension. After contacting aluminum baffles 68(which tend to cool down due to the relatively good thermal conductivityof aluminum), grease and contaminants tend to collect on the surfaces ofbaffle 68. Additionally, grease and contaminants also tend to collectonto the surfaces of baffles 70 and 72. The grease and contaminants alsotend to slide downward and collect along the bottom edge of each baffle.As grease extractor 20 is tilted forward when in use, the grease andcontaminants also tend to slide forward for collection and drainagethrough holes 97 (see FIG. 4) and 99. Holes 97 and 99 lead to aneffluent collection manifold 130 within square tube 76. The grease andcontaminants are then further collected through an effluent outletassembly 46 (see FIG. 6) in each grease extractor 20 for collection viaeffluent pipe 26 in waste housing 28 (see FIG. 1). Hence, greaseextractor 20 tends to be somewhat self-cleaning.

FIG. 4 illustrates the configuration of apertures 77 in steam pipes 76for delivering steam into slots 78. The steam is drawn in along withcontaminated air (from a cooking operation). The mixture then travelsalong paths 82 and 84, as well as paths 86 and 88, while depositinggrease and contaminants onto surfaces of baffles 64, 66, 68, 70 and 72.Baffles 64 and 66 are constructed from stainless steel which provides aneffective flame shield, or heat shield. This serves to protect and helpreduce the temperature of baffles 68, 70 and 72 (which increases greaseextraction thereon). Baffles 68, 70 and 72 are formed from aluminum,which tends to help conduct heat (and is an excellent heat sink), andkeeps them cooler. Accordingly, grease and contaminants are encouragedto further deposit onto baffles 68, 70 and 72 due to the further reducedsurface temperatures. Additionally, air is drawn through greaseextractor 20, along with cooking gases, which helps to reducetemperatures and further help to precipitate out grease fromcontaminated air (and cooking gases). This cooperation enhances theability of grease extractor 20 to remove grease and contaminants fromcontaminated air that passes therethrough.

By providing smooth surfaces on baffles 64, 66, 70 and 72, accumulatedgrease tends to slide down the surfaces and collect at the bottom fordelivery through holes 97 and 99. According to one construction, steamis continuously emitted via holes 77. According to another construction,steam is intermittently emitted via holes 77.

FIG. 5 further illustrates the ejection of steam via holes 77 spacedapart axially along each steam pipe 76 and into a respective slot 78.Path 82 leads to path 86, whereas path 84 leads to path 88. Slot 80leads into a chamber 101 where relatively clean air is passed throughapertures in diffuser plate 74 for delivery through an exhaust duct andout of a building.

FIG. 6 shows a front view of grease extractor 20, but with the bafflesde-emphasized and showing the steam pipes 76 in relation to frame 60.Additionally, a top facia plate 102 and a bottom facia plate 104 (ofstainless steel) are removably mounted over flexible rubber steam pipe106, flexible rubber effluent pipe 108 and associated steam inletassembly 44 and effluent outlet assembly 46, respectively. Frame 60,including solid bars 62, supports steam pipes 76 and assemblies 44 and46.

FIG. 7 depicts a top left corner of frame 60 in partial breakaway viewto show attachment of solid bar 62 onto a square tube 79. A steam supplyplenum 110 is provided inside of tube 79 and configured to deliver steaminto a top opening on each steam tube 76. Flexible rubber steam supplypipe (or hose) 106 is also shown covered by facia 102 of greaseextractor 20.

FIG. 8 depicts a top center view of steam inlet assembly 44. A steaminlet t-shaped fitting 112 provides an inlet for receiving steam viapipes 106 and into manifold 110 (of FIG. 7). Connectors 114, 116 and 118are used to removably couple together flexible pipes 106 onto fitting112 to facilitate removal and maintenance of individual greaseextractors 20.

FIG. 9 depicts a bottom left corner of frame 60 in partial breakawayview to show attachment of bar 62 to square tube 76 of grease extractor20. Each steam tube 76 is received through a bore in a top surface oftube 130 for securement therein via press fit or welding. A plug 120 inthe bottom end of tube 130 causes steam to be ejected from a pluralityof steam emitters, or holes 77. Effluent manifold 130 can also be seeninside of tube 76.

FIG. 10 shows a bottom center view of effluent outlet assembly 46 ofgrease extractor 20. More particularly, flexible rubber effluent outletpipes (or hoses) 108 are fastened onto an effluent outlet T-shapedfitting 122 of grease extractor 20. Connectors 124, 126 and 128 are usedto removably fasten pipes 108 onto fitting 122 to facilitate maintenanceand cleaning of grease extractor 20. Collected grease and contaminantsare drawn through an aperture 166 of fitting 122 for delivery throughpipe 108 onto effluent pipe 26 for collection into waste housing 28 (seeFIG. 1).

FIG. 11 shows grease extractor from a top edge view with a top surfacepartially removed to facilitate viewing of the first array 54, secondarray 56, and third array 58 of baffles. Holes 97 and 99 and steam pipes76 are shown in relation to arrays 54, 56, and 58. Likewise, diffuserplate 74 is also shown.

FIG. 12 shows a back side of grease extractor 20 with diffuser plate 74(of FIG. 11) removed to facilitate viewing of the arrangement of slots80 provided in third array 58. Slots 80 cooperate in array 58 to providebaffles therein. Frame 60 is also shown supporting array 58.

Steam pipe 13 is shown prior to assembly in FIGS. 13-17. A bottom brassend plug 120 is inserted (or press fit) into pipe 76 to force steam toeject via ejectors (or holes) 77. A slot 134 is provided in a top end ofpipe 76 to facilitate assembly onto the grease extractor frame. Slot 134is provided about an open end 132 of pipe 176. As shown in greaterdetail in FIG. 16, plug 120 is inserted into a bore 136 of pipe 76. Bore136 is also shown in relation with slot 134 in FIG. 17.

FIG. 18 illustrates in vertical sectional view a supply system forsupplying steam via fitting 112 through a feed tube 164 into steamsupply manifold 110 for delivery into individual bores 136 of steampipes 76 for ejection via hole 77 into a stream of contaminated air. Aframe lip extrusion 138 supplies a pair of top and bottom grooves forremovably securing facia plate 102 there along. A resilient O-ringgasket 146 (of EPDM) encircles the top portion of tube 76 to ensure thatsteam is delivered within bore 136. Another resilient gasket 142,comprising Santoprene, is configured to seal with a frame 19 (seeFIG. 1) after installation of grease extractor 20 therein. A pair of topclamps 148 are mounted to frame 60 for securing and releasing greaseextractor 20 from within frame 19 (of FIG. 1). Diffuser panel 74 is madefrom a sheet of perforated aluminum sheet metal that is folded alongeach edge and which forms a relief opening 162 at each corner. Flanges100 are also shown in relation to diffuser plate 74.

FIG. 19 illustrates in vertical sectional view the withdrawal of greaseand contaminants (effluent) via effluent outlet T-shaped fitting 122 byway of a drain tube 166 that communicates with effluent manifold 130.Effluent is received in the manifold 130 via holes 77 and 79 (see FIG.3). Another pair of clamps 150 are mounted along frame 60 for securingand releasing grease extractor 20 from frame 19 (see FIG. 1). Anotherresilient gasket (of Santoprene) 144 is provided along a bottom surfaceof frame 60 so as to seal steam extractor 20 there along. Additionalgaskets can be provided between adjacent grease extractors when they aremounted together in assembly. Furthermore, a frame lip extrusion 140 isprovided along a bottom edge of frame 60 having an upper groove and alower lip edge configured to removably secure a facia plate 104 therealong. Finally, an exemplary steam pipe 76 is shown having an internalbore 136 that communicates with individual holes 77 for rejecting steamtherethrough. A bottom end of pipe 76 is closed via a tightly fittingplug 120 which forces steam to eject the holes 77. A flange 100 is shownin relation to diffuser panel 74 and gap 162.

FIG. 20 illustrates in greater detail the configuration of pairs ofclamps 148 and 150 relative to frame 60. As shown, there are two clamps148 along a top edge of frame 60 and two clamps 150 along a bottom edgeof frame 60. Each clamp 148 is secured via a threaded fastener 154 ontoframe 60. Fastener 154 is captured for rotation within a stepped recessor bore 158 in frame 60. Fastener 154 is secured via a pair of ringclips 152 such as C-clips or E-clips. Clips 152 cooperate to retainclamp 148 along a threaded portion 150 of fastener 154. Clamp 148 (aswell as clamp 150) includes a threaded bore that is threadingly engagedalong threaded section 150. As fastener 158 is rotated, clamp 148 can bemoved toward and away from frame 60 in order to clamp and unclamp greaseextractor 20 from a neighboring frame 19 (see FIG. 1). Additionally, apair of captive screws 160 are also provided within frame 60, mainlywithin solid bar 62 along each lateral edge of frame 60.

FIG. 21 illustrates in enlarged view the relationship of clamps 148relative to an external frame 19 when clamps 148 have been secured ontoframe 19. Steam is delivered via fitting 112 and feed tube 164 fordelivery into individual steam pipes 76 for ejection via holes 77.

FIG. 22 illustrates in enlarged detail the configuration of clamps 150when secured onto exterior frame 19 so as to mount grease extractor 20within a ventilation hood of a kitchen ventilation system. Collectedgrease is accumulated and delivered via fitting 122 for withdrawal fromgrease extractor 20.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A grease extractor, comprising: a frame; a first array of convexbaffle plates carried by the frame in spaced-apart relation providing afirst ventilation slot between adjacent, convex baffle plates; a secondarray of concave baffle plates carried by the frame in spaced-apartrelation defining a second ventilation slot between adjacent, concavebaffle plates, a selected concave baffle plate offset from a respective,downstream convex baffle plate such that the first ventilation slotopens into a base portion of the concave baffle plate; and a steamejector supported proximate each ventilation slot for delivering steaminto the first ventilation slot and toward a respective one of theconcave baffle plates.
 2. The grease extractor of claim 1 wherein aselected concave baffle plate is offset a half-mode from a respectiveconvex baffle plate.
 3. The grease extractor of claim 1 furthercomprising a third array of baffle plates in spaced-apart relation anddefining a third ventilation slot therebetween and downstream of thesecond array of baffle plates.
 4. The grease extractor of claim 3wherein each baffle plate in the third array of baffle plates issupported offset a half-mode from a respective one of the concave baffleplates in the second array such that the third ventilation slot alignssubstantially with the base of the concave baffle plate and the firstventilation slot.
 5. The grease extractor of claim 4 wherein the firstarray, the second array and the third array of baffles plates are eachin substantially parallel relation with one another.
 6. The greaseextractor of claim 1 wherein the first array of convex baffle plates andthe second array of concave baffle plates are provided in substantiallyparallel, spaced-apart relation.
 7. The grease extractor of claim 3wherein the baffle plates in the third array are convex baffle plates.8. The grease extractor of claim 7 wherein the convex baffle plates inthe third array are u-shaped plates having a base and a pair ofsubstantially parallel, right-angle legs.
 9. The grease extractor ofclaim 1 wherein the convex baffle plates each comprise a central, convexportion and a pair of concave, turned-back outer portions, wherein thefirst ventilation slot is provided between adjacent turned-back portionsof respective, adjacent convex portions.
 10. The grease extractor ofclaim 6 wherein the turned-back outer portions are parallel and providethe first ventilation slot between adjacent turned-back portions ofadjacent, respective convex baffle plates.
 11. The grease extractor ofclaim 6 wherein the turned-back outer portions are parallel to a flowdirection through the grease extractor and perpendicular to the first,second, and third arrays of baffle plates.
 12. The grease extractor ofclaim 1 wherein the concave baffle plates are more thermally conductivethan the convex baffle plates.
 13. The grease extractor of claim 3wherein the third array of baffle plates are more thermally conductivethan the convex baffle plates.
 14. The grease extractor of claim 1further comprising a third array of baffle plates in substantiallyspaced-apart relation and defining a third ventilation slot therebetweenand downstream of the second array of baffle plates
 15. The greaseextractor of claim 13 wherein the concave baffle plates and the thirdarray of baffle plates are each more thermally conductive than theconvex baffle plates.
 16. The grease extractor of claim 12 wherein theconcave baffle plates are made from aluminum.
 17. The grease extractorof claim 13 wherein the baffle plates in the third array are made fromaluminum.
 18. The grease extractor of claim 1 wherein the steam ejectorcomprises a steam supply rod provided upstream of the first ventilationslot, the steam supply rod including a plurality of spaced-apartejection nozzles on a downstream side of the rod configured to ejectsteam into the first ventilation slot.
 19. The grease extractor of claim18 wherein the steam supply rod is substantially parallel to the firstventilation slot.
 20. The grease extractor of claim 1 wherein the frameis configured to support the first array and the second array andencircle an outer periphery of the first array and the second array. 21.The grease extractor of claim 20 wherein a top edge of the frameincludes a steam manifold communicating with the steam ejector todeliver a supply of steam to the steam ejector.
 22. The grease extractorof claim 21 wherein the steam ejector comprises a steam supply rodprovided upstream of and parallel to the first ventilation slot, thesteam supply rod including a plurality of spaced-apart ejection nozzleson a downstream side of the rod configured to eject steam into the firstventilation slot.
 23. The grease extractor of claim 20 furthercomprising a plurality of drainage apertures provided along a bottomedge of the frame for draining grease that accumulates along the bottomedge from the concave and convex baffle plates.
 24. The grease extractorof claim 23 wherein the drainage apertures are provided upstream of thefirst ventilation slots.
 25. The grease extractor of claim 23 whereinthe drainage apertures are provided downstream of the first ventilationslots and upstream of the second ventilation slots.
 26. The greaseextractor of claim 23 wherein the drainage apertures are providedupstream of the first ventilation slots.
 27. The grease extractor ofclaim 23 wherein the frame includes a drainage manifold along a bottomedge of the frame communicating with the drainage apertures toaccumulate grease from the drainage apertures for collection andtransfer to a collection device.
 28. The grease extractor of claim 1wherein the convex baffle plates of the first array have a u-shaped,convex cross-sectional configuration relative to an upstream side of thegrease extractor.
 29. The grease extractor of claim 1 wherein theconcave baffle plates of the second array have a u-shaped concavecross-sectional configuration relative to an upstream side of the greaseextractor.
 30. The grease extractor of claim 29 wherein the u-shapedconcave baffle plates have square corners between a central base and apair of opposed edges.
 31. The grease extractor of claim 30 wherein thesquare corners have a bend radius.
 32. The grease extractor of claim 30further comprising a third array of baffle plates in substantiallyspaced-apart relation and defining a third ventilation slot therebetweenand downstream of the second array of baffle plates, and wherein thecentral base includes an angled channel provided on a back face of thecentral base configured to divert flow into a respective thirdventilation slot.
 33. The grease extractor of claim 1 wherein each ofthe concave baffle plates includes a pair of lateral edges each foldedback to provide an inverted cuff-portion.
 34. A ventilation filter for acooking device, comprising: an array of parallel, spaced-apart convexchannels; an array of parallel, spaced-apart concave channels offset ahalf-mode and internested with the convex channels to provide circuitousflow paths therebetween; an array of parallel, spaced-apart platesoffset a half-mode from the concave channels; and a steam pipe providedbetween adjacent ones of the concave channels and configured to directsteam into a slot between the adjacent convex channels.
 35. Theventilation filter of claim 34 wherein slots are provided betweenadjacent convex channels.
 36. The ventilation filter of claim 34 whereinslots are provided between adjacent concave channels.
 37. Theventilation filter of claim 34 wherein slots are provided betweenadjacent plates.
 38. The ventilation filter of claim 34 wherein eachplate includes an edge flange extending in a forward direction.
 39. Theventilation filter of claim 38 wherein a pair of the edge flanges on oneof the plates provides a concave plate.
 40. The ventilation filter ofclaim 34 further comprising a steam plenum configured to deliver steamto the steam pipe.
 41. A method for extracting grease from cookingexhaust fumes, comprising: providing a grease extractor with convexbaffle plates, adjacent axial slots, and concave baffle plates offset ahalf-mode from the convex baffle plates; directing flow over the convexbaffle plates and into the adjacent axial slots; delivering steam intothe axial slots in a same direction as flowing exhaust fumes; splittingflow of exhaust fumes and steam exiting the axial slots into the concavebaffle plates into lateral, opposing directions, and directing the flowinto a direction reversing the direction of flow in the axial slots, andinto the concave side of the convex baffle plates; and diverting flowfrom the concave side of the convex baffle plates into the second axialslots provided between adjacent concave baffle plates.
 42. The method ofclaim 41 further comprising directing flow from the second axial slotsalong the concave side of the convex baffle plates and through a thirdlongitudinal slot in a third array of baffle plates.
 43. The method ofclaim 41 further comprising providing a base ridge on a bottom, outsideportion of the concave baffle plates and directing flow along the bottomof the concave baffle plates into the third longitudinal slot.
 44. Themethod of claim 41 further comprising providing a second array of baffleplates having a higher thermal conductivity than the first array ofbaffle plates, and collecting grease on the second baffle plates atleast in part from thermal cooling of the second baffle plates relativeto the first baffle plates.
 45. The method of claim 41 wherein the firstbaffle plates have an m-shaped cross-sectional configuration viewed froman upstream side of the grease extractor.
 46. The method of claim 45wherein the m-shaped baffle plates have a pair of vertical, outer legs.47. The method of claim 41 wherein the second baffle plates have au-shaped cross-sectional configuration viewed from a downstream side ofthe grease extractor.
 48. The method of claim 47 wherein the u-shapedbaffle plates have right angle corners.
 49. The method of claim 41further comprising providing drainage apertures along a bottom edge ofthe grease extractor, and draining accumulated grease through theapertures.